1. Field of the Invention
This invention relates to insecticide compositions and methods for controlling the breeding of insects which have aquatic breeding sites.
2. Background of the Art
In the specification of our British Pat. Nos. 1 357 952 (March 1971) and 1 557 804 (October 1976) there is disclosed a method of controlling the breeding of mosquitoes by forming an insoluble monomolecular layer on the surface of water to reduce the number of mosquito pupae and larvae.
The monomolecular layer is particularly effective in killing the mosquito at certain stages of the life cycle, namely the ovipositing female, fourth stage larva, pupa and emerging adult. It is lethal because the decrease in surface tension causes wetting of the respiratory trumpets of the pupae and larvae and also forms a physical barrier to surface penetration, thus preventing oxygen uptake from the atmosphere by the larvae and pupae. The application of monolayers to the control of mosquito juveniles is described in:
1. McMullen, A. I. and Hill, M. N., (1971), Nature, 234, No. 5323 pp 51-52.
2. McMullen, A. I., Reiter, P. and Phillips, M. C., (1977), Nature, 267, No. 5608 pp 244-245.
3. Garrett, W. D., (1976), Naval Res. Lab. Report 8020, p 13, Washington D.C.
In the specification of our British Pat. No. 1 561 088 there is disclosed a method of controlling the breeding of insects which have an aquatic phase in their life cycle by forming an insoluble foam layer on the surface of the water. This foam layer presents an impenetrable barrier to pupae and larvae of the insects, again wetting their respiratory system and preventing oxygen uptake.
The foam method is more effective than the monomolecular method in that it is effective in killing the mosquito at all stages in its life cycle, namely: ovipositing female, egg, first, second, third and fourth stage larva, pupa and emerging adult. It is, however, more expensive than the monomolecular method in both dosage and application equipment.
There are also specific toxins obtained from Bacillus thuringiensis cultures (hereinafter referred to as B.t.) and from Bacillus sphaericus cultures which are mainly effective against first, second and third stage mosquito larvae but suffer from the disadvantage that the toxin crystal is dense and rapidly sinks below the feeding zones of young larvae. It is also rapidly inactivated by particulate matter in the catchment.
U.S. Pat. No. 4,707,359 describes an insecticide composition for controlling the breeding of insects (particularly mosquitos) which have aquatic breeding sites comprises two components, the first being either an insoluble monomolecular layer, an insoluble foam layer or a duplex film layer and the second having a toxic action on larvae, the combination of the two components providing a synergistic mixture. In particular, this patent describes an insecticide composition for controlling insects which have an aquatic breeding site, comprising an effective insecticidal amount of a first component which when applied to the surface of a water catchment forms an insoluble monomolecular layer or an insoluble foam layer effective in killing insects at certain stages in their life cycle, said first component being selected from the group consisting of:
a) CmH2m+1.(OR)mnOH, b) CmH2mxe2x88x921.(OR)nOH, c) CmH2m+1.(OR.OB)nOH, d) CmH2mxe2x88x921(OR.OB)nOH, e) CmH2m+1.CO.(OR)nOH, f) CmH2mxe2x88x921.CO.(OR)nOH, g) CmHm2m+1.CO.(OR.OBnOH, and h) CmHm2mxe2x88x921.CO.(OR.OB)nOH,
where R and B are alkylenes and may be the same or different, n is an integer in the range 1 to 3 and m is an integer greater than 14, said group being exclusive of isostearyl ethoxylates; and an effective larvicidal amount of a second component comprising a mosquito larva toxin obtained during growth of bacterial cultures, the first and second components giving rise to a synergistic mixture having a greater effectiveness in control of insects than that exhibited by either the first or second component alone. There is provided an insecticide composition for controlling insects which have an aquatic breeding site comprising a first component which is capable of forming either a monomolecular layer, an insoluble foam layer or a duplex film layer on the surface of a water catchment and a second component which has a toxin action (preferably rapid) on larvae, giving rise to a synergistic mixture. The first component may be any one or more of the compounds referred to in the specification of British Pat. Nos. 1 557 804 and 1 561 088. Thus the first component may include at least one long chain compound of the general formula:
CmH2m+/xe2x88x921.(OR)nOH
or
CmH2m+/xe2x88x921.(OR.OB)nOH
and/or at least one long chain compound of the general formula:
CmH2m+/xe2x88x921.CO.(OR)nOH or CmH2m+/xe2x88x921.CO.(OR.OB)nOH
where these include branched chain isomers, but excepting isostearyl alcohol or acid.
It was asserted to be unexpected that by mixing the toxin from Bacillus thuringiensis or Bacillus sphaericus with the material forming the monomolecular layer, the toxin was retained at the surface for quite long periods and was transported or spread over wide areas. When the toxin was mixed with an insoluble foam layer the toxin is held at the surface for periods depending on the speed of breakdown of the foam, which depends on the amount applied and the extent of water pollution. Alternatively, the monomolecular layer and toxin mixture were applied to the water surface with a thin oil layer applied on top thereof, thus forming a xe2x80x9cduplex filmxe2x80x9d. These methods of applying the toxin to a water catchment resulted in a much more effective method for killing mosquitoes than by applying the monolayer, foam, thin oil or the toxin alone. Thus the combination produced a synergistic mixed product. In these formulae, R and B are alkylenes and may be the same or different, n is an integer in the range 1 to 3 and m is an integer greater than 14. The second component may be any specific mosquito larval toxin such as that obtained during growth of bacterial cultures, for example, that toxin found in B. thuringiensis H-14 (Bt-H14) or in B. sphaericus preparations, the toxin being a high molecular weight protein which splits into active sub-units inside the larvae.
U.S. Pat. No. 4,160,033 describes the use of a nonionic, autophobic, organic material with a density less than that of water, a boiling point of 170 degrees Centigrade or more, a freezing point of less than 5 degrees Centigrade, an HLB number of 10 or less, a bulk viscosity of less than 1000 Centistokes at the temperature of use, a spreading velocity of 10 cm/sec for the first 100 cm, and a surface tension effectiveness which lowers the surface tension of said body of water to 30 dynes/cm or less. The specifically disclosed materials for use within this process are described as sorbitan monooleate, a solution of 70 volume percent to less than 100 volume percent of sorbitan monooleate and 2-ethylbutanol; saturated, branched chain alcohols with a total carbon content of from 15 to 19 carbon atoms and one to three oxyethylene groups; unsaturated cis alcohols with 15 to 19 carbon atoms in the chain length; unsaturated ethers with a chain length of 12 to 18 carbon atoms and three to five oxyethylene groups; and oleyl ether with two oxyethylene groups, and combinations of these compounds. The preferred materials for use alone or in combination include sorbitan monooleate, isostearyl alcohol, lauryl ether, and oleyl ether. Such a compound or combination of compounds is capable of forming an insoluble monomolecular layer, a foam layer or, (in the presence of an oil), a duplex film, on the surface of a water catchment.
U.S. Pat. No. 5,635,194 describes the use of water-soluble, detergent-range, ethoxylated alcohols to control black fly larvae in aquatic habitats. The mechanism of larvicidal activity described in the patent relates only to persistent subsurface targeting of black fly larvae that are attached to various submerged substrates and does not describe or contemplate any activity against any aquatic species at the air-water interface. The reference is specifically silent as to effects upon immature mosquitoes at the air/water interface of aquatic habitats.
The application of film-forming compositions to aquatic sites, especially aquatic breeding sites for surface-active, aquatic breeding insects, especially for mosquito larvae and mosquito pupae, has been found to be enhanced when different compounds than those suggested in the prior art are used. The compounds according to the present invention comprise film-forming chemicals which are biodegradable, nonionic, insoluble or partially soluble in water, and include C6, C7, C8, C9, C10, and C11, alcohol ethoxylates, propoxylates, and/or alkoxylates with an average of one (1) to five (5) moles of ethylene and/or propylene oxide per mole of alcohol, and mixtures thereof. Examples of commercial materials of interest include, for example, Neodol(copyright) 91-2.5 which is a mixture of C9-C11 alcohol ethoxylates with average of 2.5 moles of ethylene oxide per mole of alcohol, Neodol(copyright) 1-3 and Neodol(copyright) 1-5 which are C11 alcohol ethoxylates with 3 and 5 moles of ethylene oxide per mole of alcohol, respectively, Alfonic(copyright) 610-3.5 Ethoxylate and Alfonic(copyright) 810-2 Ethoxylate which are C6-C10 and C8-C10 alcohol ethoxylate mixtures containing 3.5 and 2 moles of ethylene oxide per mole of alcohol, respectively, and Iconol(copyright)E DA-4 which is a C10 4-mole ethylene oxide adduct of decyl alcohol. These film-forming materials, which have shorter carbon chains than the film-forming materials described for use by the prior art show improved results in comparison with some of the longer carbon chain length compounds of the prior art.
The components of the insecticide application may be formulated for application to water in several ways. These methods include:
(1) Approximately Monomolecular Layer or Multimolecular Layer Application,
(2) Substantive or Transient Foam Application
(3) Delayed Release Application for Formation of Approximately Monomolecular Layer or Multimolecular Layers
(4) Spray Application, or
(5) Combined Application With Insecticidal Materials (e.g., as in U.S. Pat. No. 4,707,359).
Method (1) may be effected, for example, where the first component is in the form of a hydrophobic soft wax or xe2x80x9coilxe2x80x9d at ambient temperatures and is applied directly to the water surface.
Method (2) may be effected, for example, when the first component may be solid or semi-solid, it may be prepared by gradually adding it to water being stirred vigorously in a high speed mixer, emulsifier or colloid mill to form a dispersion having a concentration of from 10% to 20% w/v. A substantive foaming agent, such as a thickener, surfactant, detergent, foaming agent or the like may be combined with the film-forming compositions of the present invention for application to water. Additional film-forming materials of the prior art may be blended with the film-forming materials of the present invention. However, the film-forming materials of the present invention should comprise at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at lest 95% or even 100% by weight or volume of all organic and/or inorganic film-forming materials used in the applied compositions. The higher the proportion of the film-forming compounds of the present invention, apparently the higher the insecticidal efficacy of the compositions used, even without any toxicological insecticidal agents used. Foam formulations may also be produced most easily from monomolecular layer formulation (B) described above (but, for example, diluted with water to 1% of the active ingredient) by the injection of air, in situ generation of foam with foaming agents, or other gases using foaming equipment as described in British Pat. No. 1 561 088. It is preferable that the foam layer formed is at least 0.1 cm in thickness. The foam may be applied at a rate of 1.0 to 5.0 g of active ingredient per square meter which forms a foam layer about 0.1 to 0.5 cm in thickness and which may reduce to a single bubble layer eventually or monomolecular layer or multimolecular layer, which is still effective.
The applied insecticide composition may include an extender (either water-soluble, water-dispersible, or water-insoluble) such as water or an oil, for example a vegetable oil such as soya bean oil or coconut oil or a light mineral oil such as diesel oil, petrol oil, diesel oil, etc., but these tend to contribute undesirable contaminants to the aquatic environment and are not preferred. Dyes may be used with the composition to assist in the visibility of the application, preferably water-soluble or oil-soluble dyes, more preferably dyes which decompose or are bleached by extended exposure to air, natural light, and/or water.
The insecticide composition once formulated may be applied to water to form a monomolecular layer, a multimolecular layer (or two, three or more layers, or a layer hydrophilically or hydrophobically or coupled continuous or discontinuous layer) associated with the surface as a self-spreading suspension of xe2x80x9cslurryxe2x80x9d by means of droppers, drip-feed reservoirs, spray equipment or by sorbent and inert materials (e.g., which may be preferably biodegradable, soluble or insoluble) which have been soaked in the concentrated mixture and which float on the surface of the water or which sink in the water and quickly or slowly (as desired) releases the composition.
When the surface of the water or aquatic area to be treated is moving water, the surface must be made static by employing a physical barrier, e.g., by means of a buoyant boom tethered or anchored around the appropriate area. Suitable physical barriers are described in British Patent Specification No. 1 561 088. The preferred compositions according to the present invention contain no unspecific toxin or pollutive materials, and the materials used are biodegradable. However, pesticides such as insecticides, larvicides, pupicides, herbicides (the destruction of which can also assist in the reduction in pests by removing material essential to their habitat) and the like may be used where additional active effects are found to be necessary.
Surface-film technology has been shown to be applicable to mosquito control. Nonionic organic monomolecular or duplex films have been shown to be effective against the immature stages of most species of mosquitoes in a variety of water or aquatic environments. Laboratory and field evaluations have mainly focused on the control of larvae and pupae; however, some studies have shown the potential for controlling floating eggs/egg rafts and emerging adults or ovipositing females.
Unlike the central nervous system, endocrine system, and stomach or contact poison effects of larvicidal products such as organophosphates, phenyl-pyrazoles, growth regulators, and bacteria, the mode of action of these biodegradable surface-active films is nontoxic via a physicochemical mechanism that reduces the surface tension of the aquatic mosquito habitat causing a wetting of the tracheal structures (e.g., larval siphon or pupal trumpets) which assists in and/or causes the subsequent drowning of larvae and pupae. Since death is induced by a physical effect of the surface film at the air-water interface, resistance of mosquito populations to these types of chemicals is not expected to develop. This is a significant improvement over the use of pesticidal materials since the ability of insects to develop resistance to specific pesticides has been well documented and reported in the literature.
Although surface films have been proven to be effective in controlling mosquito larvae, the speed of action is usually slow. Larval instar, species, habitat, oxygen levels, wind speed and direction, runoff, tidal fluxes, emergent and floating vegetation, and surface debris have been shown to have a dramatic effect on the mosquito-controlling efficacy of surface films. Therefore, a surface film, mixture of surface films, or surface film formulation having a faster physical mode of action on larval mosquito populations at the air-water interface or providing more consistent delayed efficacy would help compensate for the adverse or inhibitory effects caused by the aforementioned habitat and environmental/climatological fluctuations.
Product Classification: Film-forming chemicals of the present invention are biodegradable nonionic, insoluble or partially soluble in water, and include C6, C7, C8, C9, C10, and C11 alcohol ethoxylates, propoxylates, and/or alkoxylates with an average of one (1) to five (5) moles of ethylene and/or propylene oxide per mole of alcohol, and mixtures thereof. Examples of products of interest are Neodol(copyright) 91-2.5 which is a mixture of C9-C11 alcohol ethoxylates with average of 2.5 moles of ethylene oxide per mole of alcohol, Neodol(copyright) 1-3 and Neodol(copyright) 1-5 which are C11 alcohol ethoxylates with 3 and 5 moles of ethylene oxide per mole of alcohol, respectively, Alfonic(copyright) 610-3.5 Ethoxylate and Alfonic(copyright) 810-2 Ethoxylate which are C6-C10 and C8-C11 alcohol ethoxylate mixtures containing 3.5 and 2 moles of ethylene oxide per mole of alcohol, respectively, and Iconol(copyright) DA-4 which is a C10 4-mole ethylene oxide adduct of decyl alcohol.
Film-forming product examples of interest have the following Hydrophile-Lipophile Balance No., Pour Point (xc2x0 C.), and Specific Gravity (77/77xc2x0 F.) parameters, respectively. Neodol(copyright) 91-2.5 parameters are 8.5, xe2x88x9213, and 0.925; Neodol(copyright) 1-3 parameters are 8.7, xe2x88x927, and 0.936; Neodol(copyright) 1-5 parameters are 11.2, 6, and 0.966; Alfonic(copyright) 610-3.5 Ethoxylate parameters are 10.0, xe2x88x927, and 0.95; Alfonic(copyright) 810-2 Ethoxylate parameters are 8.0, xe2x88x9215, and 0.92; and Iconol(copyright) DA-4 parameters are 11.0, xe2x88x9224, and 0.958.
Film-forming chemicals of the present invention can also be mixed with solvents such as water soluble alcohols (e.g., ethanol, methanol, or 2-propanol, etc.) to enhance, activate or synergize the film-forming chemicals; however, these solvents generally show poor efficacy against immature mosquitoes when used alone.
Product Uses: Film-forming chemicals of the present invention can be used as a partially active formulation ingredient with any chemical or microbial mosquito larvicide or pupicide (e.g., pirimiphos-methyl, lambda-cyhalothrin, temephos, chlorpyrifos, methoprene, pyriproxyfen, diflubenzuron, phenyl-pyrazole, Bacillus thuringiensis var. israelensis, Bacillus sphaericus, Spinosyns, Lagenidium giganteum, polyoxyethylene (2) isostearyl alcohol, petroleum oils, etc.) to rapidly produce multistage control (e.g., rapid larval and pupal kill) by enhancing or synergizing the action of the chemical or microbial insecticide as well as improving water-surface coverage and vegetative penetration of the product(s) mixed with the film-forming chemicals. Film-forming chemicals of the present invention can be used as a technical active ingredient for killing mosquito larvae and pupae at the air-water interface, to sink or inhibit the eclosion of floating eggs or egg rafts, and to entrap and drown ovipositing females, resting males, and emerging adults. Pupae of certain mosquito species can be significantly more sensitive to surface films than larvae. Film-forming chemicals of the present invention can also be used to control the surface-active aquatic stages of certain non-mosquito invertebrate pests such as nuisance aquatic insects (e.g., midges, sand flies). The use of these film-forming chemicals in fish farming or aquaculture to control predacious insects is also proposed.
The activity of the compounds and compositions of the present invention is effective against surface-active aquatic species during their surface-active stage. The surface active stage is when the aquatic species lives at or near the surface of the aquatic habitat or passes through the air-aquatic habitat interface, or breeds and breaths within or near the air-aquatic habitat interface.
Product Formulation. Film-forming chemicals of the present invention can be used alone as a neat formulation or can be mixed neat or with water, water soluble alcohols, surface active chemicals, oils or conventional mosquito larvicides. The formulation of choice for each film-forming chemical, mixture or formulation will be dependent on the physicochemical characteristics of the film-forming chemical or chemicals utilized to control the target pest(s). Film-forming chemicals or formulations can also be formulated into solid compositions that have a specific gravity less than, equal to, or greater than 1.0 (e.g., granules, pellets, or briquets). Soluble or insoluble, biodegradable or erodable carriers (which are preferred) for the film-forming compositions of the present invention may be non-superabsorbent polymers, natural products (e.g., papers, cellulosic solids, water-insoluble porous materials which absorb or adsorb the film-forming material within the structure, water-soluble porous materials which absorb or adsorb the film-forming material within the structure, porous containers which merely slowly release a volume of the film-forming material, porous containers which both dissolve and physically release volumes of the film-forming composition through pores, and the like. In general, selection of an effective application rate can depend on habitat depth, surface debris, emergent and surface vegetation, organic matter, microbial and algal concentration, the specific target species, and the developmental stage of the target species.
Product Application Rates: Film-forming chemicals of the present invention can be applied by ground or aerial techniques as technical, water-base, solvent-base, oil-base or solid formulations as well as admixtures with pesticides or pesticide formulations at application rates of ca. 0.3-2.0 gallons of film-forming chemical(s)/surface acre of water.